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Rain and Snow Spotter Information



Rain gage Information


Location and Exposure of Rain Gages


The exposure of a rain gage is very important for obtaining accurate measurements. Gages should not be located close to isolated obstructions such as trees and buildings, which may deflect precipitation due to erratic turbulence. Gages should not be located in wide-open spaces or on elevated sites, such as tops of buildings, because of wind and the resulting turbulence problems.

The best location for a gage is where the gage is uniformly protected in all directions, such as in an opening in a grove of trees. The height of the protection should not exceed twice its distance from the gage. As a general rule, the windier the gage location is, the greater the precipitation error will be. Try to locate the gage within easy access and where you'll be reminded to read and empty the gage daily.


Installation and Maintenance of Rain Gages


Mount the rain gage firmly on a post (4"x4" or 2 2"x4"s nailed together) so that the top of the gage is level and about 6 inches higher than the top of the post. Gage may be washed periodically with mild soap or dishwasher detergent and using a bottle brush. Do not use solvents or abrasives and do not wash in dishwasher.


Care and Use of Rain Gage in Winter*


When snow is likely to fall or when precipitation in the gage is likely to freeze, remove the funnel and the inner measuring tube from the outer 4" overflow container. Do not allow accumulated water to freeze in the gage, especially the inner measuring tube. The plastic can bend and crack, leading to inaccurate rain measurements.

Water equivalent of frozen precipitation (snow, ice pellets, etc.) that has fallen into the outer container of the gage can be determined by following these steps:

1. Bring the overflow container that contains snow into a warm place.

2. Wait for the precipitation to melt.

3. Pour the melted precipitation into the measuring tube, using funnel if you wish.

4. Measure this as you would measure rain.

Melting the frozen precipitation can be accelerated by carefully measuring an amount of warm water in the measuring tube, pouring this in the overflow can with the precipitation, letting it melt, measuring the total amount of melted water and precipitation, then subtracting the amount of water added.

* Slight differences may exist in care and use of different type rain gages